The serial decoding (any decoding) is done after the data is captured.So it is impossible to trigger on a decoded pattern.

However it is possible to do int with the SDK and a lot of effort I have done it before with CAN decoding in real-time (this was a 500kbps CAN data stream)So a 9600 bps or 115.2 kbps can be done in software with the SDK in real time.

The main problem is the SDK wont support save the data in .psdata files so it is impossible to see the data in picoscope.

You can also use a audrino or a raspberry pi to listen to the serial data and toggle a GPIO pin when the data is seen on the serial port, you have a trigger signal to trigger the scope (the trigger will always be after the data is occurred).

If you use one of the deep memory oscilloscope then you can collect / decode huge amounts of serial data. The filter command can then be used to search / find any specific data string you are after.

For the 2000 series with smaller internal memories this is still possible for slower serial protocols - they can capture 100,000,000 samples of data in USB streaming mode. Max sampling rate in PicoScope for this mode is 1MS/s.